Data Pathfinders

Related Content

Wildfires Data Pathfinder

Data pathfinders are pathways to the most commonly-used datasets within NASA’s Earth science collections. The goal of the pathfinders is to aid new data users in discovering data and visualizations of the data. While there are numerous datasets for any fire-related measurement, this pathfinder showcases datasets that are used by natural resource managers, wildland fire managers, emergency responders, and federal agencies to aid in decision making.

A prescribed fire is applied to a Pinus nigra stand in Portugal. (Courtesy P. Fernandes)

About the Data

According to the Fourth National Climate Assessment, climate change has made its appearance, afflicting the world with extreme weather conditions, including increased heat waves, rising sea levels, and increasing devastation from wildfires, to name just a few. NASA is interested in all of these issues, particularly for fires because of their environmental, societal, and economic impacts. How are changes in climate boosting the increase in fire activity across the globe and what can be done to mitigate the impacts?

A combination of ground- and satellite-based data provides a unique view of the globe to better understand active fires and hotspots, thermal anomalies, and aerosol transport of smoke and particulate matter. In addition, climatological and vegetative measurements help scientists, researchers, and decision makers prepare for risk and response to events as well as aiding in forecasting events and assessing the post-event impacts.

NASA, in cooperation with its partner agencies and organizations, has a series of instruments that provide data to assist with forecasting, monitoring and assessment. NASA’s Earth science data products are validated, meaning the accuracy has been assessed over a widely distributed set of locations and time periods via several ground-truth and validation efforts.

Tools for Data Access and Visualization

Earthdata Search provides a means of accessing all of NASA’s Earth science data across all distributed active archive centers. It provides the only means to access all data regardless of where the data are archived. Within Earthdata Search, you can subset using temporal and geographic constraints. Some data can be customized once the data of interest are selected; to do this, add the data of interest to your project and then click download all.

In the project area, you can select to customize your granule. You can reformat the data and output as HDF, NetCDF, ASCII, KML or a GeoTIFF. You can also choose from a variety of projection options. Lastly you can subset the data, obtaining only the bands that are needed.

Panoply

HDF and NetCDF files can be viewed in Panoply, a cross-platform application that plots geo-referenced and other arrays. Panoply offers additional functionality, such as slicing and plotting arrays, combining arrays, and exporting plots and animations.

• Data recipe for downloading a Giovanni map, as NetCDF, and converting to quantified map data in the form of lat-lon-data value ASCII text.

Worldview

Worldview is a visualization tool to interactively browse global, full-resolution satellite imagery layers and then download the underlying data. Many of the imagery layers are updated within three hours of observation, essentially showing the entire Earth as it looks "right now". View current natural hazards and events using the Events tab which reveals a list of natural events, including wildfires, tropical storms, and volcanic eruptions.

Worldview's Events tab provides information about events, such as tropical cyclones, wildfires, volcanic eruptions, and even large iceberg movement. Hurricane Barry, as shown in this image, traveled from the Gulf into Louisiana in July 2019.

Animate the imagery over time. Do a screen by screen comparison of data for different time periods or a comparison of different datasets.

Hurricane Maria was a category 5 storm that devastated numerous places, most notably Puerto Rico, in September 2017. In the Woldview comparison, selecting a date pre-storm and then one post-storm shows the nighttime lights over the island, and how the storm affected electricity, even months after.

Benefits and Limitations of using Satellite Data

The United States is fortunate to have numerous ground-based measurements for assessing water storage and atmospheric particulate matter. However, this is not the case in other countries and in more rural areas of the United States. Satellite data provides more regional to global spatial coverage; some of the information is available in near real-time allowing for more efficient disaster response. With satellite data, comparisons can be made using pre-event and post-event imagery, providing information on smoke and ash transport, burn severity, vegetation loss, and so much more. Incorporating satellite data with in-situ data (ground-based measurements) in modeling programs makes for a more robust forecasting system.

While the data provides a more global view, the coarse spatial resolution makes it difficult to detect small fires or field level events. In addition, polar-orbiting satellites only pass over the same spot every 1-2 days or sometimes every 16+ days, providing for a much coarser temporal resolution not adequate to monitor the dynamics of a burning fire. Passive satellites (those that use energy being emitted from the Earth for measurements) are not able to penetrate cloud or vegetation cover. This challenge can lead to the inability to see a fire, or the size and radiative power of small fires. Finding the right data, at the required spatial and temporal resolution for your interest, is key.

Applications of the Data

Scientists, researchers, land managers, and decision makers are using wildfire data in numerous ways (to see how the data is being used, check out the Data User Profiles section of the Wildfire Articles page). Wildfire data can be used to forecast events. By acquiring data on precipitation, soil moisture, drought severity, topography, land surface temperatures, and vegetation density and extent, land and/or wildlife managers can perform pre-fire mapping to indicate potential areas of risk. Near real-time wildfire data, exploring the estimated extent of total area burned and fire radiative power, can be used to assess risk in a given area and develop a more efficient strategy for response. Wildfire data can be used in post-fire mapping, incorporating total burned area, burn severity, and vegetation regrowth.

Risk and Response - Near Real-time

Aerosols/smoke plumes and transport

Terra MODIS Corrected Reflectance imagery of Camp Fire, 2018.

Aerosols and suspended particles in the air that are made up of smoke and dust from burning fires can be tracked and measured by instruments aboard NASA Earth observing satellites. The NASA Worldview application provides the capability to interactively browse over 800 global, full-resolution satellite imagery layers and download the underlying data. Many of the imagery layers are updated within three hours of observation, essentially showing the entire Earth as it looks "right now."

Using MODIS or VIIRS imagery, you can follow a smoke plume and its movement through time. You can also assess the aerosol optical depth (which can be converted to particulate matter with specific algorithms), carbon monoxide, and sulfur dioxide at the fire location, where and when available. Worldview also allows you to capture a snapshot, create an animated gif, compare imagery over time or compare two different imagery layers for the same date.

Aerosols absorb and scatter incoming sunlight, which reduces visibility and increases the optical depth. Satellite-derived AI products are useful for identifying and tracking the long-range transport of smoke from wildfires or biomass burning events. Currently there are two satellite products measuring AI, the Aura Ozone Monitoring Instrument (OMI) and Suomi-NPP’s Ozone Mapping and Profiler Suite (OMPS). AI indicates the presence of ultraviolet (UV)-absorbing particles in the air (aerosols); the higher the AI, the higher the concentration in the atmosphere. For both satellites, the spatial resolution is 2 km and the temporal resolution is daily.

• AI from OMPS in WorldviewAI from OMPS includes a newer product, PyroCumuloNimbus, which makes it easier to track the extent and spread of pyroCb and other high-aerosol events. Typically the AI signal remains below 5.0 for most smoke and dust events, the OMPS AI product with an AI range of 0.0 to 5.0 satisfies the needs of most users. However, the AI signal for pyroCb events, which are both dense and high in the atmosphere, easily can be much larger than 5.0. In fact, the highest AI value ever observed (55.0) occurred during a pyroCb event in August 2017.

AOD indicates the level at which particles in the air (aerosols) prevent light from traveling through the atmosphere. From an observer on the ground, an AOD of less than 0.1 is “clean” - characteristic of clear blue sky, bright sun and maximum visibility. As AOD increases to 0.5, 1.0, and greater than 3.0, aerosols become so dense that the sun is obscured.

• AERONETGround-based AOD measurements are available online at the Aerosol Robotic Network (AERONET).

•
AOD MODIS Data in WorldviewAqua and Terra's Moderate Resolution Imaging Spectroradiometer Combined Value-Added Aerosol Optical Depth layer is a value-added layer based on MODIS Level 2 aerosol products. The layer can give a quick, synoptic view of the level of aerosols in the atmosphere.

In addition to the particulate matter, numerous trace gases are found in the atmosphere during and after a fire event. These trace gases, like carbon monoxide (CO) and sulfur dioxide (SO2), are harmful pollutants that can impact public health. Data for trace gases are available from a variety of different satellites. For CO, the Atmospheric Infrared Sounder (AIRS) onboard the Aqua satellite provides the best global coverage at 2 km resolution and twice daily measurements (day and night). AIRS also provides measurements of SO2. Two other instruments, OMI and OMPS (descriptions above) provide information on SO2 at the lower troposphere, middle troposphere, and upper troposphere/stratosphere layers.

• AIRS CO Total Column (Day/Night) in WorldviewIndicates the amount of CO in the total vertical column profile of the atmosphere (from Earth’s surface to top-of-atmosphere) and is measured in parts per billion by volume (ppbv).

• OMI/OMPS SO2 in WorldviewIndicates the column density of sulfur dioxide at different layers of the atmosphere and is measured in Dobson Units (DU). OMI data are available from 2005-present and OMPS from 2012-present.

There are some differences between the fire datasets that must be considered. Each of these instruments has a different spatial and temporal resolution. MODIS data are at 1km and are acquired daily (Terra satellite passes over in the morning and Aqua in the afternoon), whereas VIIRS are at 375m and are acquired daily, with improved nighttime performance over MODIS. The NOAA-20 VIIRS instrument, data to be made available soon, follows the same orbit as Suomi-NPP but lags behind by about 50 minutes.

Ground observations versus output display for MODIS sensor.

The thermal anomalies/fire NRT data are basically a snapshot in time, showing what is occurring at the moment the data was acquired. It is determined by a contextual algorithm that utilizes the infrared or thermal radiation of the fires. Each MODIS active fire represents the center of a 1km pixel that is flagged by the algorithm as containing one or more fires within the pixel (see figure to right). Because VIIRS has a higher resolution, it can pick up fires that MODIS overlooks, especially those in relatively small areas.

It is important to note that the NRT products are not considered science quality because predicted geolocation is used. Science quality data, which are an internally consistent, well-calibrated record of the Earth’s geophysical properties to support science, are available with an approximate two to three months lag.

There are two primary ways of exploring NRT fire data through the Fire Information for Resource Management System (FIRMS): through an interactive map or by direct download of the NRT data. The interactive map provides NRT and the full archive of global MODIS and VIIRS fire locations. It also enables users to view the MODIS Terra/Aqua Global Burned Area data product (with an approximate 4-month lag between the date of burn and burned area data product in FIRMS)

Active fire data are available for download for any area of interest, in NRT and from the full archive.

Fire Forecasting

Many factors contribute to a fire, its intensity and its severity, including changing weather patterns, land cover, vegetative health, drought conditions, and changing land use or land management. As such, it’s important to monitor contributing factors in order to predict the formation of a fire and how it will move through the environment. NASA has several datasets for making these predictions.

Vegetation Density and Extent

Normalized Difference Vegetation Index (NDVI) provides a means to assess vegetation health in a given area. Very low values of NDVI (0.1 and below) correspond to barren areas of rock, sand, or snow. Moderate values represent shrub and grassland (0.2 to 0.3), while high values indicate temperate and tropical rainforests (0.6 to 0.8). Aqua and Terra's Moderate Resolution Imaging Spectroradiometer (MODIS) NDVI data can be accessed via the following:

• Science quality, or higher-level “standard” data products can be accessed via Earthdata Search; datasets are available as HDF files which can be opened using Panoply or customizable to GeoTIFF.

NASA’s Precipitation Measurement Missions provide a continuous long-term record (over 20 years) of precipitation data through the Tropical Rainfall Measuring Mission (TRMM) and the Global Precipitation Measurement (GPM) mission; TRMM was launched in 1997 and collected data through 2015, while GPM was launched in 2014 and is still operational. With the GPM mission, measurements increased in accuracy, improved detection of light rain and snow, and extended the spatial coverage.

These products are available individually or have been integrated, TRMM into the TRMM Multi-satellite Precipitation Algorithm (TMPA) and GPM into the Integrated Multi-satellitE Retrievals for GPM (IMERG), with a global constellation of satellites to yield improved spatial/temporal precipitation estimates with a temporal resolution of 30 minutes. IMERG’s multiple runs accommodate different user requirements for latency and accuracy (Early = 4 hours for flash flood events, Late = 12 hours for crop forecasting, and Final = three months for research with the incorporation of rain gauge data).

In addition, among IMERG and Land Data Assimilation System (LDAS), the Advanced Microwave Scanning Radiometer 2 (AMSR2) instrument, on-board the Global Change Observation Mission – Water 1 (GCOM-W1) satellite, collects data that indicates the rate at which precipitation is falling on the surface of the ocean, and is measured in millimeters per hour (mm/hr).

• IMERG from Earthdata SearchEarly, Late and Final precipitation data on the half hour or one day timeframe. Data are in NetCDF or HDF format and can be opened using Panoply. Data are available from 2014.

• TMPA from Earthdata SearchRainfall estimate at 3 hours, 1 day or NRT and accumulated rainfall at three hours and one day. Data are in HDF format and can be opened using Panoply. Data are available from 1997.

• Data products can be visualized as a time-averaged map, an animation, seasonal maps, scatter plots, and time series through an online interactive tool, Giovanni. For more information on choosing a type of plot, see the Giovanni User Manual.

• IMERG from GiovanniSelect a map plot, date range and region, and determine your variable and then plot the data. Data can be downloaded as GeoTIFF. Data are only available from 2014.

• TMPA from GiovanniSelect a map plot, date range and region, and determine your variable and then plot the data. Data can be downloaded as GeoTIFF.

• Science quality, or higher-level “standard” data products can be accessed via Earthdata Search; MODIS and VIIRS data sets are available as HDF files and can be opened using Panoply, but are also customizable to GeoTIFF:

Soil moisture is important in forecasting fire events as the dryness of the soil contributes to the overall fire potential in the area. Satellite data can provide a synoptic view of soil moisture across the globe. Although ground- based measurements are at a higher resolution, the data are often sparse and have limited coverage. The preferred measurement should be chosen based upon your needs.

SMAP's rotating golden antenna functions like a satellite dish to focus radio waves from Earth's surface into a collector on the spacecraft. Image: NASA JPL/CaltechNASA's Soil Moisture Active Passive (SMAP) satellite measures the moisture in the top 5cm of the soil globally every three days, at a resolution of 10-40km. The Advanced Microwave Scanning Radiometer 2 (AMSR2) instrument on the Global Change Observation Mission - Water 1 (GCOM-W1) provides a NRT product, which is a daily measurement of surface soil moisture.

NASA, in collaboration with other agencies, has also developed models of soil moisture content, incorporating satellite information with ground-based data when available. These models are part of the Land Data Assimilation System (LDAS), of which there is a global collection (GLDAS) and a US national collection (NLDAS).

• Science quality, or higher-level “standard” data products can be accessed via Earthdata Search; MODIS and VIIRS datasets are available as HDF files and can be opened using Panoply, but are also customizable to GeoTIFF:

• Data products can be visualized as a time-averaged map, an animation, seasonal maps, scatter plots, and time series through an online interactive tool, Giovanni. For more information on choosing a type of plot, see the Giovanni User Manual.

Knowing the topography of an area is important so that fire managers and emergency management professionals can anticipate areas of risk, including direction and speed of wind, landslide potential and runoff.

The Shuttle Radar Topography Mission (SRTM) provides a digital elevation model of all land between 60 degrees north and 56 degrees south, about 80% of all Earth’s landmass. The ASTER Global Digital Elevation Model (ASTER GDEM) coverage spans from 83 degrees north latitude to 83 degrees south, encompassing 99% of Earth's landmass. Elevation data are at a spatial resolution of 30m for both missions.

Post-Fire Impacts

The regional impacts of wildfires include not only burned area, but also changes in runoff patterns and landslide potential. While some areas allow for ground-based measurements of these post-fire impacts, areas that are remote or that have rugged terrain can make ground-based measurements impractical. Remotely-sensed data provide a means to extend our knowledge in these areas.

• MODIS Corrected Reflectance Bands 7-2-1 in WorldviewWorldview Tour provides stories to help you learn more about the visualization tool, the satellite imagery we provide and events occurring around the world. This story takes you on a tour of the Camp Fire event, November 8, 2018 north of Sacramento, California. An example of MODIS Corrected Reflectance, bands 7-2-1, is shown in slide 2.

Burn severity is the effect of fire on ecosystem properties, often defined by the degree of mortality of vegetation (relating to soil heating, consumption of litter). Using satellite imagery from Landsat or MODIS allows for pre and post-fire comparisons and a change detection approach. One of the most effective ways to discriminate is by generating a normalized burn ratio. To calculate this, using Landsat data, see the Applied Sciences Remote Sensing Training on Introduction to Remote Sensing for Wildfire Applications.

• Data products can be visualized as a time-averaged map, an animation, seasonal maps, scatter plots, and time series through an online interactive tool, Giovanni. For more information on choosing a type of plot, see the Giovanni User Manual.

• MODIS NDVI from GiovanniSelect a map plot, date range and region and then plot the data. Data can be downloaded as GeoTIFF.

NASA’s Precipitation Measurement Missions provide a continuous long-term record (over 20 years) of precipitation data through the Tropical Rainfall Measuring Mission (TRMM) and the Global Precipitation Measurement (GPM) mission; TRMM was launched in 1997 and collected data through 2015, while GPM was launched in 2014 and is still operational. With the GPM mission, measurements increased in accuracy, improved detection of light rain and snow, and extended the spatial coverage.

These products are available individually or have been integrated, TRMM into the TRMM Multi-satellite Precipitation Algorithm (TMPA) and GPM into the Integrated Multi-satellitE Retrievals for GPM (IMERG), with a global constellation of satellites to yield improved spatial/temporal precipitation estimates with a temporal resolution of 30 minutes. IMERG’s multiple runs accommodate different user requirements for latency and accuracy (Early = 4 hours for flash flood events, Late = 12 hours for crop forecasting, and Final = three months for research with the incorporation of rain gauge data).

In addition, among IMERG and Land Data Assimilation System (LDAS), the Advanced Microwave Scanning Radiometer 2 (AMSR2) instrument, on-board the Global Change Observation Mission – Water 1 (GCOM-W1) satellite, collects data that indicates the rate at which precipitation is falling on the surface of the ocean, and is measured in millimeters per hour (mm/hr).

• IMERG from Earthdata SearchEarly, Late and Final precipitation data on the half hour or one day timeframe. Data are in NetCDF or HDF format and can be opened using Panoply. Data are available from 2014.

• TMPA from Earthdata SearchRainfall estimate at 3 hours, 1 day or NRT and accumulated rainfall at three hours and one day. Data are in HDF format and can be opened using Panoply. Data are available from 1997.

• Data products can be visualized as a time-averaged map, an animation, seasonal maps, scatter plots, and time series through an online interactive tool, Giovanni. For more information on choosing a type of plot, see the Giovanni User Manual.

• IMERG from GiovanniSelect a map plot, date range and region, and determine your variable and then plot the data. Data can be downloaded as GeoTIFF. Data are only available from 2014.

• TMPA from GiovanniSelect a map plot, date range and region, and determine your variable and then plot the data. Data can be downloaded as GeoTIFF.

Knowing the topography of an area is important so that fire managers and emergency management professionals can anticipate areas of risk, including direction and speed of wind, landslide potential and runoff.

The Shuttle Radar Topography Mission (SRTM) provides a digital elevation model of all land between 60 degrees north and 56 degrees south, about 80% of all Earth’s landmass. The ASTER Global Digital Elevation Model (ASTER GDEM) coverage spans from 83 degrees north latitude to 83 degrees south, encompassing 99% of Earth's landmass. Elevation data are at a spatial resolution of 30m for both missions.

• SRTM data from Earthdata SearchThese data were acquired in 2000 and are in HGT format, which can be opened in most Geographic Information Systems (GIS), such as ArcGIS or QGIS. Data are also customizable to GeoTIFF.

Other NASA Assets of Interest

Earthdata has tutorials for utilizing the monthly burned area and thermal anomalies/fire data from MODIS Terra/Aqua. Tutorials are also provided from the Earthdata YouTube channel.

External Fire-Related Resources

The Global Wildfire Information System is a joint initiative of the Group on Earth Observations and the Copernicus Programs. The Global Wildfire Information System (GWIS) aims to bring together existing information sources, including NASA’s MODIS and VIIRS data, to provide a comprehensive view and evaluation of fire regimes and fire effects at a global level.

• GWIS Current Situation ViewerViewer provides a fire danger forecast as well as a rapid damage assessment, which includes active fires, burnt area, and fire emissions (sulfur dioxide, nitrogen oxides, and particulate matter). The viewer also allows for some basic statistical analysis.

NOAA also maintains several fire and smoke products from the geostationary orbiting satellites, which typically have a much coarser spatial resolution but more frequent overpasses.